354 research outputs found

    Critical intellectual resources for praxis in physical education teacher education : the limits to rationality

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    This study focuses on the way four student-teachers engage with critical social discourses in a year-long physical education unit. The student-teachers were encouraged to examine and (re)construct their pedagogy through their interactions with critical discourses. Drawing on their personal theories and actions, the study examines the extent to which critical intellectual resources can provide pedagogical frames of reference that are \u27practical and non-ideal\u27. Using a critical ethnographic methodology the students\u27 interactions with critical social discourses are diagnosed across three levels. The first level is the case study presentations of each student\u27s engagement with the critical intellectual resources and the extent to which they were able to understand and implement them. The second level involves an interpretation of the individual cases that is informed by Brian Fay\u27s (1987) metatheoretical reconstruction of the critical social sciences. In the third stage of diagnosis the study focuses on retheorising critical aspirations for praxis pedagogy in physical education. Critical scholars within the physical education arena argue that critical praxis represents a pedagogy based on a \u27world view\u27 of the potential for agents to engage in a rational reordering of their qualitative existence. The essence of their claim is that critical discourses have the potential to facilitate a mode of praxis through which physical education teachers might better recognise, understand, critique and transform their values and practices. However, there is broad recognition that the translation of social-critical discourses into a pedagogic context is highly problematic. Interpretation of the study is provided by Fay\u27s (1987) \u27limits to change\u27 thesis which recognises that critical aspirations must ultimately be adopted and implemented by real people in real settings. As a diagnostic frame of reference, Fay insists that a \u27complete\u27 critical theory [of physical education] be simultaneously scientific, critical, practical and non-ideal. In seeking to temper the "e; over-rationalistic"e; tendency of the critical project he recognises the historical, embedded, embodied and traditional nature of human existence Criticisms of critical theories of education traverse a number of philosophic perspectives. Recent post-structural criticisms of truth regimes, knowledge-power differentials, rationality and agency have seriously destabilised modernist justifications of the critical agenda. Critical theories of physical education have not been absolved of such criticism. A prominent element of this study is its promotion of a dialectical relationship between agency and structure to extend critical conceptualisations of physical education pedagogy. Through the mediation of structural determinism and self-determination this research proffers a means of practically advancing a critical praxis in physical education. The conclusion of this thesis outlines some broad recommendations pertaining to the introduction of social critical discourses in physical education teacher education

    Streaming interactive proofs

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    An interactive proof is a conversation between a powerful machine, the ‘prover’, and a ‘verifier’ with low resources. The aim of the conversation is for the prover to convince the verifier about the output of a function (that is computationally or space intensive to evaluate) over some shared data set. The concept of streaming interactive proofs (SIPs) considers a verifier with very small space, who streams the shared data, and then engages in an interactive protocol with the prover. Our work begins by looking to improve protocols for the practical verification of outsourced data analysis. We explore non-interactive and multi-round protocols for vector and matrix multiplications and analyse the real-world practicality of these approaches. We demonstrate how these protocols can be used in data analysis, considering the numerical concerns when rounding is required. We investigate the costs for the verifier, while trying to keep the overheads for the prover at a minimum, and discuss bottlenecks. Finally, we introduce the entirely new concept of Streaming Zero Knowledge for interactive proofs, which is the adaptation of regular SIPs where now the verifier learns no additional information about the data set besides the truth of the statement the prover is trying to prove. We show several examples and build up a powerful multipurpose protocol in order to showcase the strengths of this new model

    The Legacy of Space Shuttle Flight Software

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    The initial goals of the Space Shuttle Program required that the avionics and software systems blaze new trails in advancing avionics system technology. Many of the requirements placed on avionics and software were accomplished for the first time on this program. Examples include comprehensive digital fly-by-wire technology, use of a digital databus for flight critical functions, fail operational/fail safe requirements, complex automated redundancy management, and the use of a high-order software language for flight software development. In order to meet the operational and safety goals of the program, the Space Shuttle software had to be extremely high quality, reliable, robust, reconfigurable and maintainable. To achieve this, the software development team evolved a software process focused on continuous process improvement and defect elimination that consistently produced highly predictable and top quality results, providing software managers the confidence needed to sign each Certificate of Flight Readiness (COFR). This process, which has been appraised at Capability Maturity Model (CMM)/Capability Maturity Model Integration (CMMI) Level 5, has resulted in one of the lowest software defect rates in the industry. This paper will present an overview of the evolution of the Primary Avionics Software System (PASS) project and processes over thirty years, an argument for strong statistical control of software processes with examples, an overview of the success story for identifying and driving out errors before flight, a case study of the few significant software issues and how they were either identified before flight or slipped through the process onto a flight vehicle, and identification of the valuable lessons learned over the life of the project

    Contrasting Development of Canopy Structure and Primary Production in Planted and Naturally Regenerated Red Pine Forests

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    Globally, planted forests are rapidly replacing naturally regenerated stands but the implications for canopy structure, carbon (C) storage, and the linkages between the two are unclear. We investigated the successional dynamics, interlinkages and mechanistic relationships between wood net primary production (NPPw) and canopy structure in planted and naturally regenerated red pine (Pinus resinosa Sol. ex Aiton) stands spanning ≥ 45 years of development. We focused our canopy structural analysis on leaf area index (LAI) and a spatially integrative, terrestrial LiDAR-based complexity measure, canopy rugosity, which is positively correlated with NPPw in several naturally regenerated forests, but which has not been investigated in planted stands. We estimated stand NPPw using a dendrochronological approach and examined whether canopy rugosity relates to light absorption and light–use efficiency. We found that canopy rugosity increased similarly with age in planted and naturally regenerated stands, despite differences in other structural features including LAI and stem density. However, the relationship between canopy rugosity and NPPw was negative in planted and not significant in naturally regenerated stands, indicating structural complexity is not a globally positive driver of NPPw. Underlying the negative NPPw-canopy rugosity relationship in planted stands was a corresponding decline in light-use efficiency, which peaked in the youngest, densely stocked stand with high LAI and low structural complexity. Even with significant differences in the developmental trajectories of canopy structure, NPPw, and light use, planted and naturally regenerated stands stored similar amounts of C in wood over a 45-year period. We conclude that widespread increases in planted forests are likely to affect age-related patterns in canopy structure and NPPw, but planted and naturally regenerated forests may function as comparable long-term C sinks via different structural and mechanistic pathways

    Environmental characterization facilitate G × E interaction to highlight the role of stay-green traits for genetic gain

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    Environmental characterization (EC) one influential approach for understanding the performance of genotypes in different environments. Sometimes interactions between environment and genotype limit the genetic gain for complex traits in breeding programs, especially drought. Stay green lines are able to retain green leaf area longer than standard lines leading to superior adaptation under water-limitation. Modelling framework has been used analytically in breeding to dissect complex traits, such as yield under water limitation, into critical trait components (e.g. stay-green, flowering time, root architecture). Characterization can help to select more heritable genotypes that can be subjected to high throughout phenotyping, and make more sensible targets for genomic selection by the following search aims: (1) Characterise stressed environments (accounting for climate and soil characteristics, management practices, and crop development) to characterise the timing and severity of the stress and non-stress, (2) Identify the potentially adaptive cultivars and traits in each specific environment, and (3) Determine the correlation between stay-green traits and yield in the different environment types

    Multivariate Genomic Selection and Potential of Rapid Indirect Selection with Speed Breeding in Spring Wheat

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    Genomic selection (GS) can be effective in breeding for quantitative traits, such as yield, by reducing the selection cycle duration. Speed breeding (SB) uses extended photoperiod and temperature control to enable rapid generation advancement. Together, GS and SB can synergistically reduce the breeding cycle by quickly producing recombinant inbred lines (RILs) and enabling indirect phenotypic selection to improve for key traits, such as height and flowering time, prior to field trials. In addition, traits measured under SB (SB traits) correlated with field-based yield could improve yield prediction in multivariate GS. A 193-line spring wheat (Triticum aestivum L.) training population (TP), tested for grain yield in the field in multiple environments, was used to predict grain yield of a 350-line selection candidate (SC) population, across multiple environments. Four SB traits measured on the TP and SC populations were used to derive principal components, which were incorporated into multivariate GS models. Predictive ability was significantly increased by multivariate GS, in some cases being twice as high as univariate GS. Based on these results, an efficient breeding strategy is proposed combining SB and multivariate GS using yield-correlated SB traits for yield prediction. The potential for early indirect SB phenotypic selection for targeted population improvement prior to trials was also investigated. Plant height and flowering time showed strong relative predicted efficiency to indirect selection, in some cases as high as direct field selection. The higher selection intensity and rate of generation turnover under SB may enable a greater rate of genetic gain than direct field phenotyping

    Assessment of a Novel Pediatric Resident Simulation Curriculum

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    Aim: To assess the efficacy of a newly implemented resident simulation curriculum at a medium sized pediatric residency program. Background: Many pediatric residency programs incorporate high-fidelity simulation into their curriculum, but there is limited data discussing the utility/educational impacts of a longitudinal/standardized/multimodal simulation curriculum. Several studies of simulation-based training have employed “self-efficacy” as a barometer for trainee education and performance 1,2,. The level of a person’s self-efficacy can influence their behavior and may be a pivotal factor in performance. We have implemented a newly devised standardized, multimodal resident simulation curriculum and used resident self-efficacy to assess its effectiveness. Methods: Participants were UMass Pediatric and Med/Peds residents. Implementation of our curriculum occurred at the start of the 2016-2017 academic year. Surveys were administered to all residents prior to curriculum implementation and at 6 months post-implementation. They assessed resident self-efficacy with regards to specific technical/procedural skills (i.e. running a code, performing intubation, etc.) and resident confidence in their ability to identify/manage specific pediatric disease presentations (i.e. respiratory failure, tachyarrhythmia, etc.). Data was pooled and averaged for each resident class separately. We predetermined a 10% change in self-efficacy to be a clinically significant difference. Results: 36 of 40 residents completed the initial survey and 31 completed the 6-month follow-up. PGY1 residents reported improved self-efficacy for 4 PALS-related skills and 8 pediatric case presentations. Similarly, PGY2 residents reported improved self-efficacy for 3 PALS-related skills and 6 pediatric case presentations. Conversely, PGY3/4 residents reported no significant change in self-efficacy for any survey question. Conclusions: These results suggest that our newly implemented longitudinal, standardized, multidisciplinary, multi-modal simulation curriculum has significantly improved resident self-efficacy related to core Pediatric Advanced Life-Support (PALS) skills/topics, with the greatest impact affecting our PGY1 class. Further study and curriculum development will attempt to address this issue

    Categorizing the severity of paralytic shellfish poisoning outbreaks in the Gulf of Maine for forecasting and management

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    Author Posting. © The Author(s), 2013. This is the author's version of the work. It is posted here by permission of Elsevier for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part II: Topical Studies in Oceanography 103 (2014): 277-287, doi:10.1016/j.dsr2.2013.03.027.Development of forecasting systems for harmful algal blooms (HABs) has been a long-standing research and management goal. Significant progress has been made in the Gulf of Maine, where seasonal bloom forecasts are now being issued annually using Alexandrium fundyense cyst abundance maps and a population dynamics model developed for that organism. Thus far these forecasts have used terms such as “significant”, “moderately large” or “moderate” to convey the extent of forecasted paralytic shellfish poisoning (PSP) outbreaks. In this study, historical shellfish harvesting closure data along the coast of the Gulf of Maine were used to derive a series of bloom severity levels that are analogous to those used to define major storms like hurricanes or tornados. Thirty-four years of PSP-related shellfish closure data for Maine, Massachusetts and New Hampshire were collected and mapped to depict the extent of coastline closure in each year. Due to fractal considerations, different methods were explored for measuring length of coastline closed. Ultimately, a simple procedure was developed using arbitrary straight-line segments to represent specific sections of the coastline. This method was consistently applied to each year’s PSP toxicity closure map to calculate the total length of coastline closed. Maps were then clustered together statistically to yield distinct groups of years with similar characteristics. A series of categories or levels was defined (“Level 1: Limited”, “Level 2: Moderate”, and “Level 3: Extensive”) each with an associated range of expected coastline closed, which can now be used instead of vague descriptors in future forecasts. This will provide scientifically consistent and simply defined information to the public as well as resource managers who make decisions on the basis of the forecasts.Research support provided through the Woods Hole Center for Oceans and Human Health, National Science Foundation (NSF) Grants OCE-0430724, and OCE-0911031; and National Institute of Environmental Health Sciences (NIEHS) Grant 1-P50-ES012742-01, the ECOHAB Grant program through NOAA Grant NA06NOS4780245, and the PCM HAB Grant program through NOAA Grant NA11NOS4780023

    Diffusive and ballistic current spin-polarization in magnetron-sputtered L1o-ordered epitaxial FePt

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    We report on the structural, magnetic, and electron transport properties of a L1o-ordered epitaxial iron-platinum alloy layer fabricated by magnetron-sputtering on a MgO(001) substrate. The film studied displayed a long range chemical order parameter of S~0.90, and hence has a very strong perpendicular magnetic anisotropy. In the diffusive electron transport regime, for temperatures ranging from 2 K to 258 K, we found hysteresis in the magnetoresistance mainly due to electron scattering from magnetic domain walls. At 2 K, we observed an overall domain wall magnetoresistance of about 0.5 %. By evaluating the spin current asymmetry alpha = sigma_up / sigma_down, we were able to estimate the diffusive spin current polarization. At all temperatures ranging from 2 K to 258 K, we found a diffusive spin current polarization of > 80%. To study the ballistic transport regime, we have performed point-contact Andreev-reflection measurements at 4.2 K. We obtained a value for the ballistic current spin polarization of ~42% (which compares very well with that of a polycrystalline thin film of elemental Fe). We attribute the discrepancy to a difference in the characteristic scattering times for oppositely spin-polarized electrons, such scattering times influencing the diffusive but not the ballistic current spin polarization.Comment: 22 pages, 13 figure

    Cardiometabolic Plasticity in Response to a Short-Term Diet and Exercise Intervention in Young Hispanic and NonHispanic White Adults

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    BACKGROUND: Young adult Mexican Americans (MA) exhibit lower insulin sensitivity (Si) than nonHispanic whites (NHW), even when controlling for fitness and adiposity. It is unclear if MA are as responsive to the same lifestyle intervention as NHW. OBJECTIVE: We developed a model to examine cardiometabolic plasticity (i.e., changes in Si and plasma lipids) in MA compared to NHW adults in response to a diet-exercise intervention. DESIGN: Sedentary subjects (20 NHW: 11F, 9M, 23.0 y, 25.5 kg/m(2); 17 MA: 13F, 4M, 22.7 y, 25.4 kg/m(2)) consumed their habitual diets and remained sedentary for 7 days, after which fasting blood samples were obtained, and a 3-h intravenous glucose tolerance test (IVGTT) was performed with the insulin area under the curve (IAUC) used to estimate Si. Subjects then completed a 7-day diet/exercise intervention (diet: low saturated fat, low added sugar, high fiber; exercise: cycling, six total sessions lasting 40-45 min/session at 65% VO(2) max). Pre-intervention tests were repeated. RESULTS: Pre intervention IAUC was 28% higher (p<0.05) in MA (IAUC pre  =  2298 µU*180 min/mL) than in NHW (IAUC = 1795 µU*180 min/mL). Following the intervention, there was a significant reduction in IAUC in MA (29%) and NHW (32%), however, the IAUC remained higher (p<0.05) for MA (post  = 1635 µU*180 min/mL) than for NHW (post = 1211 µU*180 min/mL). Pre test plasma lipids were not different in MA compared to NHW. Plasma cholesterol and TG concentrations significantly improved in both groups, but concentrations of low density lipoprotein-cholesterol and small dense LDL particles significantly improved only in the NHW. CONCLUSION: With a short-term diet-exercise intervention, the magnitude of improvements in Si and serum cholesterol and TG in Hispanics are similar to those in NHW. However, because at the outset MA were less insulin sensitive compared to NHW, within the short timeframe studied the ethnic gap in insulin sensitivity remained
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